(1) Field of the Invention
The present invention relates to the cleavage of hexose or pentose monosaccharides selectively to three (3) carbon products, primarily lactic acid and glyceric acid. C5 pentose monosaccharides can produce acetic acid and glycolic acid as well. In particular, the present invention relates to the production, isolation and purification of lactic acid and glyceric acid using a solid base catalyst such as an anionic ion exchange resin at ambient pressures.
(2) Description of the Related Art
The prior art describes the separation of lactic acid from other acid impurities as evidenced by US2003/0155298 which is incorporated by reference herein. There is no prior art relative to the selective cleavage of a hexose or pentose monosaccharide to a C3 or C2 product using a strongly basic solid base such as an anionic ion exchange resin. The prior art uses water soluble bases; however, the yields of lactic acid are less than 60% (Bruijn, J. M., et al., Int. Sugar 101-104 (1994); Ellis, A. V., et al., J. Org. Chem. 67, 8469-8474 (2002); Bruijn, J. M., et al., Recl. Trav. Chim. Pays-Bas 106, 35-43 (1987); U.S. Pat. No. 2,382,889 to Lock; U.S. Pat. No. 2,024,556 to Braun; and Bruijn, J. M., et al., Sugar Technology Review 13 21-52 (1986)). The prior art also uses hydrogenolysis to convert the sugar alcohols of hexoses and pentoses (200° C., 1000 psi H2, metal catalyst and a base) which are difficult and expensive conditions. There is a need for an improved process.